In the past, one common way of handling sonobuoys has been to make each of a size to fit in a standard container which serves as both a storage container and as a launch tube. The container was provided with a launching mechanism, for example a cartridge actuated device, which, upon actuation, ejected the sonobuoy into the water. There are a number of "standard" sonobuoy sizes. By way of example, one widely used size is known as an "A" size and its container is a cylindrical tube approximately 3 feet long and 5 inches in diameter.
Changes in the missions of sonobuoys and advances in the sonobuoy art have made it desirable to reduce the size of sonobuoys. Such reduction, if done indiscriminately, could result in a proliferation of new containers, each of a size and configuration to accomodate a new smaller sonobuoy, many of which would be incompatible with each other and with existing storage and launching equipment both aground and aloft. On the other hand, if one were simply to place two or more small sonobuoys in one of the existing standard containers, they might well be launched simultaneously which is usually not a desirable mode of operation.